<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>js数据类型</title>
</head>
<body>

</body>
<script>
    // alert(typeof 3);
    // alert(typeof 3.14);
    // alert(typeof "hello");
    // alert(typeof 'hello');
    // alert(typeof true);
    // alert(typeof false);
    // alert(typeof null);
    // alert(typeof null);
    //
    // var a;
    // alert(typeof a);

    let name = "tom";
    let age = 18;
    console.log("大家好" + name + "今年" + age + "岁");
    console.log(`大家好${name}今年${age}岁`);
</script>
</html>